WEDNESDAY, Nov. 2, 2016 (HealthDay News) -- More than half of Americans have at least one chronic disease, mental illness or problem with drugs or alcohol, according to a new study.

"The health of individuals in the U.S.A. is increasingly being defined by complexity and multimorbidity, the co-occurrence of two or more chronic medical conditions," said the study authors, Elizabeth Lee Reisinger Walker and Dr. Benjamin Druss.

They emphasized that people with multiple health issues need more access to care and better coordination among their health care providers.

The Emory University researchers examined public health records to find out what percentage of U.S. adults have chronic medical conditions, mental illness or substance abuse problems, and how many were also living in poverty.

Chronic medical conditions looked at in the study included asthma, cirrhosis, diabetes, heart disease, hepatitis, high blood pressure, HIV/AIDS, lung cancer, pancreatitis and stroke, according to the report.

The study, published online recently in Psychology, Health & Medicine, found that nearly 40 percent had at least one chronic medical condition. In addition, about 18 percent had been diagnosed with a mental illness in the past year, and about 9 percent abused drugs or alcohol during that time.

Overall, about 15 percent were living in poverty, the investigators found. Among those with chronic conditions, many had less than a high school education, were unemployed, were receiving government aid and had no health insurance.

The study found that, overall, roughly 6 percent had a chronic medical condition as well as a mental illness. About 2 percent had both a mental illness and a substance abuse problem; slightly fewer had a chronic disease along with a drug or alcohol problem.

The researchers reported that 2.2 million Americans have all three issues -- a chronic medical condition, a mental illness, and a drug or alcohol problem.

Adults with a mental illness had more than triple the rate of drug or alcohol problems, and were nearly 1.5 times more likely to have an ongoing medical issue. They were also 1.2 times more likely to live in poverty, the findings showed.

"Just over half of adults in the U.S. have one or more chronic condition, mental disorder, or dependence on substances. These conditions commonly overlap with each other and with poverty, which contributes to poor health," Walker said in a journal news release. "In order to promote overall health, it is important to consider all of a person's health conditions along with poverty and other social factors."

The study authors are with the Rollins School of Public Health at Emory University in Atlanta.